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  Subjects -> ENGINEERING (Total: 2269 journals)
    - CHEMICAL ENGINEERING (190 journals)
    - CIVIL ENGINEERING (181 journals)
    - ELECTRICAL ENGINEERING (101 journals)
    - ENGINEERING (1203 journals)
    - ENGINEERING MECHANICS AND MATERIALS (389 journals)
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CHEMICAL ENGINEERING (190 journals)                     

Showing 1 - 0 of 0 Journals sorted alphabetically
AATCC Journal of Research     Full-text available via subscription   (Followers: 5)
ACS Sustainable Chemistry & Engineering     Hybrid Journal   (Followers: 2)
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 4)
Acta Polymerica     Hybrid Journal   (Followers: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 20)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 6)
Advanced Chemical Engineering Research     Open Access   (Followers: 29)
Advanced Powder Technology     Hybrid Journal   (Followers: 15)
Advances in Applied Ceramics     Hybrid Journal   (Followers: 4)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 24)
Advances in Chemical Engineering and Science     Open Access   (Followers: 52)
Advances in Polymer Technology     Hybrid Journal   (Followers: 12)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Anti-Corrosion Methods and Materials     Hybrid Journal   (Followers: 6)
Applied Petrochemical Research     Open Access   (Followers: 2)
Asia-Pacific Journal of Chemical Engineering     Hybrid Journal   (Followers: 7)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 13)
Biofuel Research Journal     Open Access   (Followers: 4)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Brazilian Journal of Chemical Engineering     Open Access   (Followers: 3)
Bulletin of Chemical Reaction Engineering & Catalysis     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 3)
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Catalysts     Open Access   (Followers: 6)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
Chemical and Engineering News     Free   (Followers: 10)
Chemical and Materials Engineering     Open Access   (Followers: 9)
Chemical and Petroleum Engineering     Hybrid Journal   (Followers: 10)
Chemical and Process Engineering     Open Access   (Followers: 23)
Chemical and Process Engineering Research     Open Access   (Followers: 20)
Chemical Engineering & Technology     Hybrid Journal   (Followers: 32)
Chemical Engineering and Processing: Process Intensification     Hybrid Journal   (Followers: 17)
Chemical Engineering and Science     Open Access   (Followers: 15)
Chemical Engineering Communications     Hybrid Journal   (Followers: 13)
Chemical Engineering Education     Full-text available via subscription  
Chemical Engineering Journal     Hybrid Journal   (Followers: 31)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 22)
Chemical Engineering Research Bulletin     Open Access   (Followers: 10)
Chemical Engineering Science     Hybrid Journal   (Followers: 23)
Chemical Geology     Hybrid Journal   (Followers: 15)
Chemical Papers     Hybrid Journal   (Followers: 2)
Chemical Product and Process Modeling     Hybrid Journal   (Followers: 3)
Chemical Reviews     Full-text available via subscription   (Followers: 147)
Chemical Society Reviews     Full-text available via subscription   (Followers: 39)
Chemical Technology     Open Access   (Followers: 13)
ChemInform     Hybrid Journal   (Followers: 7)
Chemistry & Industry     Hybrid Journal   (Followers: 4)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry of Materials     Full-text available via subscription   (Followers: 158)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Chemical Letters     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemical Engineering     Full-text available via subscription   (Followers: 4)
Chinese Journal of Chemical Physics     Hybrid Journal   (Followers: 1)
Coke and Chemistry     Hybrid Journal   (Followers: 1)
Coloration Technology     Hybrid Journal  
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computer Aided Chemical Engineering     Full-text available via subscription   (Followers: 1)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
CORROSION     Full-text available via subscription   (Followers: 18)
Corrosion Engineering, Science and Technology     Hybrid Journal   (Followers: 33)
Corrosion Reviews     Hybrid Journal   (Followers: 3)
Crystal Research and Technology     Hybrid Journal   (Followers: 5)
Current Opinion in Chemical Engineering     Open Access   (Followers: 8)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
Eksergi     Open Access  
Emerging Trends in Chemical Engineering     Full-text available via subscription   (Followers: 2)
European Polymer Journal     Hybrid Journal   (Followers: 41)
Fibers and Polymers     Full-text available via subscription   (Followers: 5)
Fluorescent Materials     Open Access   (Followers: 1)
Focusing on Modern Food Industry     Open Access   (Followers: 2)
Frontiers of Chemical Science and Engineering     Hybrid Journal   (Followers: 2)
Gels     Open Access  
Geochemistry International     Hybrid Journal   (Followers: 2)
Handbook of Powder Technology     Full-text available via subscription   (Followers: 5)
Heat Exchangers     Open Access   (Followers: 2)
High Performance Polymers     Hybrid Journal  
Hungarian Journal of Industry and Chemistry     Open Access  
Indian Chemical Engineer     Hybrid Journal   (Followers: 5)
Indian Journal of Chemical Technology (IJCT)     Open Access   (Followers: 9)
Indonesian Journal of Chemical Science     Open Access   (Followers: 1)
Industrial & Engineering Chemistry     Full-text available via subscription   (Followers: 10)
Industrial & Engineering Chemistry Research     Full-text available via subscription   (Followers: 21)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 3)
Industrial Gases     Open Access  
Info Chimie Magazine     Full-text available via subscription   (Followers: 3)
International Journal of Chemical and Petroleum Sciences     Open Access   (Followers: 2)
International Journal of Chemical Engineering     Open Access   (Followers: 7)
International Journal of Chemical Reactor Engineering     Hybrid Journal   (Followers: 3)
International Journal of Chemical Technology     Open Access   (Followers: 5)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Food Science     Open Access   (Followers: 3)
International Journal of Industrial Chemistry     Open Access   (Followers: 1)
International Journal of Polymeric Materials     Hybrid Journal   (Followers: 5)
International Journal of Science and Engineering     Open Access   (Followers: 4)
International Journal of Waste Resources     Open Access   (Followers: 3)
Journal of Chemical Engineering & Process Technology     Open Access   (Followers: 3)
Journal of Applied Crystallography     Hybrid Journal   (Followers: 5)
Journal of Applied Electrochemistry     Hybrid Journal   (Followers: 11)
Journal of Applied Polymer Science     Hybrid Journal   (Followers: 109)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 9)
Journal of Bioprocess Engineering and Biorefinery     Full-text available via subscription  
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 10)
Journal of Chemical and Biological Interfaces     Full-text available via subscription   (Followers: 1)
Journal of Chemical Ecology     Hybrid Journal   (Followers: 6)
Journal of Chemical Engineering     Open Access   (Followers: 17)
Journal of Chemical Engineering and Materials Science     Open Access   (Followers: 2)
Journal of Chemical Science and Technology     Open Access   (Followers: 4)
Journal of Chemical Sciences     Partially Free   (Followers: 17)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 10)
Journal of Chemical Theory and Computation     Full-text available via subscription   (Followers: 14)
Journal of CO2 Utilization     Hybrid Journal   (Followers: 2)
Journal of Crystallization Process and Technology     Open Access   (Followers: 7)
Journal of Environmental Chemical Engineering     Hybrid Journal   (Followers: 3)
Journal of Food Measurement and Characterization     Hybrid Journal  
Journal of Food Processing & Technology     Open Access   (Followers: 1)
Journal of Fuel Chemistry and Technology     Full-text available via subscription   (Followers: 4)
Journal of Geochemical Exploration     Hybrid Journal   (Followers: 1)
Journal of Industrial and Engineering Chemistry     Hybrid Journal   (Followers: 1)
Journal of Information Display     Hybrid Journal   (Followers: 1)
Journal of Inorganic and Organometallic Polymers and Materials     Partially Free   (Followers: 8)
Journal of Modern Chemistry & Chemical Technology     Full-text available via subscription   (Followers: 2)
Journal of Molecular Catalysis A: Chemical     Hybrid Journal   (Followers: 5)
Journal of Non-Crystalline Solids     Hybrid Journal   (Followers: 7)
Journal of Organic Semiconductors     Open Access   (Followers: 4)
Journal of Physics and Chemistry of Solids     Hybrid Journal   (Followers: 5)
Journal of Polymer and Biopolymer Physics Chemistry     Open Access   (Followers: 4)
Journal of Polymer Engineering     Hybrid Journal   (Followers: 8)
Journal of Polymer Research     Hybrid Journal   (Followers: 6)
Journal of Polymer Science Part C : Polymer Letters     Hybrid Journal   (Followers: 6)
Journal of Polymers     Open Access   (Followers: 2)
Journal of Polymers and the Environment     Hybrid Journal   (Followers: 1)
Journal of Pure and Applied Chemistry Research     Open Access   (Followers: 1)
Journal of the American Chemical Society     Full-text available via subscription   (Followers: 271)
Journal of the Bangladesh Chemical Society     Open Access  
Journal of the Brazilian Chemical Society     Open Access   (Followers: 2)
Journal of The Institution of Engineers (India) : Series E     Hybrid Journal   (Followers: 1)
Journal of the Pakistan Institute of Chemical Engineers     Open Access   (Followers: 1)
Journal of the Taiwan Institute of Chemical Engineers     Hybrid Journal   (Followers: 2)
Journal of Water Chemistry and Technology     Hybrid Journal   (Followers: 8)
Jurnal Bahan Alam Terbarukan     Open Access  
Jurnal Inovasi Pendidikan Kimia     Open Access   (Followers: 1)
Jurnal Reaktor     Open Access  
Jurnal Teknologi Dan Industri Pangan     Open Access   (Followers: 1)
Konversi     Open Access  
Korean Journal of Chemical Engineering     Hybrid Journal   (Followers: 3)
Main Group Metal Chemistry     Hybrid Journal   (Followers: 1)
Materials Chemistry and Physics     Full-text available via subscription   (Followers: 14)
Materials Science and Applied Chemistry     Open Access  
Materials Sciences and Applied Chemistry     Full-text available via subscription  
Modern Chemistry & Applications     Open Access  
Molecular Imprinting     Open Access  
Nanocontainers     Open Access  
Nanofabrication     Open Access  
Noise Control Engineering Journal     Full-text available via subscription   (Followers: 2)
Ochrona Srodowiska i Zasobów Naturalnych : Environmental Protection and Natural Resources     Open Access  
Petroleum Chemistry     Hybrid Journal   (Followers: 1)
Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B     Full-text available via subscription   (Followers: 4)
Plasma Processes and Polymers     Hybrid Journal   (Followers: 1)
Plasmas and Polymers     Hybrid Journal  
Polymer     Hybrid Journal   (Followers: 109)
Polymer Bulletin     Hybrid Journal   (Followers: 7)
Polymer Composites     Hybrid Journal   (Followers: 14)
Polyolefins Journal     Open Access  
Powder Technology     Hybrid Journal   (Followers: 14)
Recyclable Catalysis     Open Access   (Followers: 1)
Research on Chemical Intermediates     Hybrid Journal  
Reviews in Chemical Engineering     Hybrid Journal   (Followers: 5)
Revista Cubana de Química     Open Access  
Revista ION     Open Access  
Revista Mexicana de Ingeniería Química     Open Access  
Rubber Chemistry and Technology     Full-text available via subscription   (Followers: 2)
Russian Chemical Bulletin     Hybrid Journal   (Followers: 2)
Russian Journal of Applied Chemistry     Hybrid Journal   (Followers: 1)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 58)
Solid Fuel Chemistry     Hybrid Journal  
South African Journal of Chemical Engineering     Open Access   (Followers: 2)
South African Journal of Chemistry     Open Access   (Followers: 2)
Surface Engineering and Applied Electrochemistry     Hybrid Journal   (Followers: 5)
Sustainable Chemical Processes     Open Access   (Followers: 2)
Synthesis Lectures on Chemical Engineering and Biochemical Engineering     Full-text available via subscription  
The Canadian Journal of Chemical Engineering     Hybrid Journal   (Followers: 3)
The Chemical Record     Hybrid Journal   (Followers: 1)
Theoretical Foundations of Chemical Engineering     Hybrid Journal   (Followers: 2)
Transition Metal Chemistry     Hybrid Journal   (Followers: 2)
Transylvanian Review of Systematical and Ecological Research     Open Access  
Visegrad Journal on Bioeconomy and Sustainable Development     Open Access   (Followers: 2)
Zeitschrift für Naturforschung B : A Journal of Chemical Sciences     Open Access   (Followers: 1)

           

Journal Cover Chemical Engineering Science
  [SJR: 1.073]   [H-I: 135]   [23 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0009-2509
   Published by Elsevier Homepage  [3040 journals]
  • Evaluation of two-group interfacial area transport equation model for
           vertical small diameter pipes against high-resolution experimental data
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Akshay J. Dave, Annalisa Manera, Matthias Beyer, Dirk Lucas, Matthew Bernard
      Two-phase flow is ubiquitous in industrial, chemical and thermal plants alike. The current state-of-the-art system-code model for predicting fluid transport in two-phase flows is the two-fluid model. In the two-fluid transport model, the coupling of mass, momentum and energy transfer between phases is highly dependent on interfacial area transfer terms. Several research efforts in the past have been focused on the development of an interfacial area transport equation model (IATE) in order to eliminate the drawbacks of static regime flow maps currently used in best-estimate thermal-hydraulic system codes. The IATE attempts to model the dynamic evolution of the vapor/liquid interface by accounting for the different interaction mechanisms affecting gaseous phase transport. The further development and validation of IATE models has been hindered by the lack of adequate experimental data in regions beyond the bubbly flow regime. At the Helmoltz-Zentrum Dresden-Rossendorf (HZDR) experiments utilizing wire-mesh sensors have been performed over all flow regimes, establishing a database of high-resolution (in space and time) data. A 52.3mm diameter pipe with a 16 by 16 wire-mesh sensor operating at 2.5kHz is utilized in the air-water experimental database used in this work. There are a total of 37 tests (with varying superficial gas and liquid velocities, at approximately 0.25MPa). Analysis of IATE performance in the bubbly flow and slug flow regimes is presented. The performance of the Fu-Ishii two-group IATE model is evaluated. In all regions, the interfacial area concentration for small bubbles is predicted well. The model performs poorly in high void fraction regimes, in which large irregularly shaped bubbles are present. The interaction mechanisms that support and deter performance of the IATE model are highlighted. A sensitivity analysis indicates modification of the group-2 wake entrainment coefficient may extend the validity of the Fu-Ishii model. An optimization study is presented to further explore improving IATE performance. It is concluded that the availability of accurate data at high void fractions from the HZDR facility provides a path to improve IATE performance.

      PubDate: 2017-01-13T06:22:31Z
       
  • Three-dimensional numerical study of heat transfer and mixing enhancement
           in a circular pipe using self-sustained oscillating flexible vorticity
           generators
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Samer Ali, Charbel Habchi, Sébastien Menanteau, Thierry Lemenand, Jean-Luc Harion
      In this paper, heat transfer and mixing performances are studied using three-dimensional numerical simulations of fluid-structure interactions. To this aim, a multifunctional heat exchanger/reactor geometry is investigated, consisting of a circular pipe where five arrays of four equally spaced trapezoidal vortex generators are inserted and inclined in a reversed position opposite to the flow direction with an angle of 45° with respect to the pipe wall. A periodic rotation of 45° is applied to the tabs arrays. Two cases are numerically studied: one using flexible vortex generators (FVG) that deform due to fluid forces applied on the structures and the other using conventional non deformable rigid vortex generators (RVG). For the FVG configuration, the tabs oscillate without addition of any external source of energy except that of the fluid flow itself, leading to a passive but dynamic way to perform vortex formation to disturb the flow. Both flow regimes are laminar with a constant Reynolds number of 1500. The flow structures are analyzed using the proper orthogonal decomposition (POD) technique and the effect of tabs oscillation on vortices creation, suppression and dislocation is highlighted. The effect of self-sustained free elastic tabs oscillation on heat transfer and mixing performances is numerically investigated by comparing the FVG with its corresponding RVG configuration. The Nusselt number comparison shows that the free tabs oscillation can improve the overall heat transfer of about 118% with respect to an empty pipe whereas it is about 97% for the RVG study. Finally, to assess the mixing performance, the transport of a passive scalar initially divided into two different concentrations in the pipe is numerically analyzed through the mixing index value. The FVG configuration shows a drastic improvement of the mixture quality at the exit of the pipe with an increase of 195% with respect to the RVG case, leading to much shorter and compact mixers and reactors.

      PubDate: 2017-01-13T06:22:31Z
       
  • Effect of sintering on the reactivity of copper-based oxygen carriers
           synthesized by impregnation
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Juan C. Maya, Farid Chejne, Suresh K. Bhatia
      A grain model based on population balances for redox reactions of copper-based oxygen carriers is developed. It considers the effects of grain size distribution and sintering, and a new expression for the aggregation frequency, which takes into account the sintering mechanisms and synthesis method, is deduced. In order to validate the model, six copper-based oxygen carriers were synthesized by excess wet impregnation and by incipient impregnation. They were characterized by BET surface area, BJH porosimetry, and SEM microscopy. Model results were compared with experimental data acquired by thermogravimetry during several redox cycles and the model was able to predict the conversion drop over the course of redox cycles due to sintering. It was found that copper-based oxygen carriers synthesized by incipient impregnation are more strongly affected by sintering than those prepared via excess wet impregnation, and finally it is shown that metallic copper sinters during oxidation, resolving a controversy in this regard that has existed in the literature.

      PubDate: 2017-01-13T06:22:31Z
       
  • Pressure drop in packed beds of angular parallelepipeds, including the
           effects of particle interference
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Élizabeth Trudel, William Hallett
      Pressure loss measurements are reported in packed beds of seven different shapes of angular parallelepiped, ranging from nearly cubical particles to thin flat chips, and compared with a number of available correlations, most of which underpredicted the pressure loss. All particle types when packed in the bed were found to overlap each other to some degree, and the extent of this was estimated from photographs, from which the average particle surface area effectiveness η was found to range from 0.69 to 0.85. The pressure loss correlation of Nemec and Levec (2005) was modified to include the effects of particle overlap, and values of η deduced by fitting to the measurements. The resulting values agreed well with those estimated from photographs, indicating that a pressure loss test can be used to assess particle overlap in a bed of known particle geometry. The range of Reynolds numbers covered was about 150–900. This is expected to be useful in assessing effective surface areas for heat and mass transfer and chemical reaction in packed beds.

      PubDate: 2017-01-13T06:22:31Z
       
  • Analysis of powder rheometry of FT4: Effect of air flow
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Wenguang Nan, Mojtaba Ghadiri, Yueshe Wang
      Understanding of particle flow behaviour as a function of strain rate is of great interest in many items of equipment of industrial processes, such as screw conveyors, impeller mixers, and feeders. The traditional commercial instruments for bulk powder flow characterisation, such as shear cells, operate at low shear strain rates, and are not representative of unit operations under dynamic conditions. In recent years, the FT4 powder rheometer of Freeman Technology has emerged as a widely used technique for characterising particle flow under dynamic conditions of shear strain rate; yet little is known about its underlying powder mechanics. We analyse the effect of gas flow on the flow behaviour of cohesionless particles in FT4 both experimentally and by numerical simulations using the combined discrete element method (DEM) and computational fluid dynamics (CFD). The results show that the effect of gas flow on the flow energy could be described by the resultant fluid-induced drag on the particles above the blade position as the impeller penetrates the bed. The strain rate in front of the blade is mainly determined by the impeller tip speed, and is not sensitive to the gas flow and particle size. The flow energy correlates well with the shear stress in front of the blade. They both increase with the strain rate and are significantly reduced by the upward gas flow.
      Graphical abstract image

      PubDate: 2017-01-13T06:22:31Z
       
  • The frequency of periodic structures in vertical pneumatic conveying of
           large particles
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Barry J. Azzopardi
      The transport of larger particles, defined as type D in the classification of Geldart (1973), by pneumatic conveying, is characterised by periodic structures, namely slugs. The frequency of these slugs in vertical pipes shows a trend similar to that seen for equivalent structures in gas-liquid flows. A simple equation has been derived to specify the apparent viscosity of the dense particle areas. From the non-dimensional relationship describing the frequency, its dependence on different variables can be identified. It can be inferred that pressure will not have a strong effect on frequency. There is a complication when the piping consists of a horizontal pipe followed by a bend and a vertical section. If there is slug flow in the horizontal pipe, the frequency in the vertical pipe could be the same as that in the horizontal section.
      Graphical abstract image

      PubDate: 2017-01-13T06:22:31Z
       
  • Asphalt-derived high surface area activated porous carbons for the
           effective adsorption separation of ethane and ethylene
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Wanwen Liang, Yufan Zhang, Xingjie Wang, Ying Wu, Xin Zhou, Jing Xiao, Yingwei Li, Haihui Wang, Zhong Li
      We reported novel asphalt–based activated carbons (A-ACs) with high C2H6/C2H4 adsorption capacity and selectivity. A series of A-ACs were prepared by a one-step preparation method and characterized. The adsorption performances of A-ACs for ethane/ethylene were examined. Results showed that the sample A-ACs prepared at 800°C and the KOH/asphalt ratio=4 exhibited ultra-high BET area of 3111m2/g and its pore volume reached 1.92cm3/g. Their surface O and N contents gradually decreased with activation temperature or KOH/asphalt ratio at which A-ACs were prepared. More interestingly, A-ACs showed significantly preferential adsorption of C2H6 over C2H4. It could be ascribed to the stronger interaction of C2H6 with the surfaces of A-ACs by hydrogen bonds compared to C2H4, which were revealed by Density functional theory calculation. Its C2H6 adsorption capacity was up to 7.2mmol/g at 100kPa and 25°C and its C2H6/C2H4 adsorption selectivity for typical cracked gas mixture (15:1 ethylene/ethane) was in the range of 3.2–16.3 at the pressure below 100kPa, higher than the most reported ethane-adsorbents. Additionally, the isosteric heat of ethane and ethylene adsorption on A-ACs were lower than those on π-complexation adsorbents. Therefore, these excellent adsorption properties would make A-ACs as a type of promising adsorbents for adsorption separation of C2H6/C2H4.
      Graphical abstract image

      PubDate: 2017-01-13T06:22:31Z
       
  • Selection of efficient solvent in solvent-aided thermal recovery of
           bitumen
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Nasser Sabet, Hassan Hassanzadeh, Jalal Abedi
      In solvent-assisted thermal recovery of bitumen, steam and solvent transfer their latent heat to the oil sands, mobilize the bitumen and co-condense on steam-bitumen interface. The mixing of heated bitumen with solvents further reduces its viscosity and the mobilized oil drains by gravity toward the production well. Co-injection of steam and solvent results in a gravitationally unstable diffusive boundary layer leading to convective dissolution of bitumen and solvent and thereby increases the oil recovery. We present a linear stability analysis to study the growth of convective instabilities and determine the onset of convective dissolution and the initial wavelength of instabilities. The scaling relations obtained from the linear stability are used to find the optimum solvent for solvent-aided thermal recovery processes by taking into account the azeotropic nature of solvent and steam co-condensation. The results show that an n-alkane carbon number range between 7 and 9 leads to earlier onset of convective dissolution, which is in agreement with the results of reservoir simulations. This study provides a fast screening method for selection of efficient solvent for the solvent-aided thermal recovery processes. In addition, the predicted initial wavelengths of instabilities facilitates selection of the proper grid size in numerical simulation of solvent and steam recovery processes.
      Graphical abstract image

      PubDate: 2017-01-06T02:33:39Z
       
  • Aldehyde functionalized graphene oxide frameworks as robust membrane
           materials for pervaporative alcohol dehydration
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Dan Hua, Rajesh Kumar Rai, Yu Zhang, Tai-Shung Chung
      To glue the graphene oxide (GO) nanosheets more firmly and to fabricate more stable GO membranes for long-term applications, three types of graphene oxide framework (GOF) membranes have been molecularly constructed via the aldehyde-functionalization of GO and a pressure assisted ultrafiltration method. The resultant GOF membranes not only possess GO/aldehyde covalent bonds but also display adjustable microstructural properties, confirmed by FTIR, XPS, XRD and positron annihilation spectroscopy (PAS). All aldehyde modified GOF membranes exhibited much improved separation performance for ethanol dehydration via pervaporation, as compared with the pristine GO membrane. The GOF membranes were also tested for the dehydration of ethanol, isopropanol, and n-butanol at different feed temperatures. Excellent separation performance at 60°C for n-butanol dehydration was obtained with a high flux of 2593gm−2 h−1 and the water concentration in permeate of 99.7wt%. Importantly, the pervaporation stability of GOF membranes at a relatively high temperature was investigated for the first time. The membranes performed well for the dehydration of alcohols at 60°C within a long period of 160–200h.
      Graphical abstract image

      PubDate: 2017-01-06T02:33:39Z
       
  • An isoperimetric optimal control problem for a non-isothermal chemical
           reactor with periodic inputs
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): A. Zuyev, A. Seidel-Morgenstern, P. Benner
      In this paper, we study the optimal control problem for a continuous stirred tank reactor (CSTR) that represents a reaction of the type “A →product”. The reactor dynamics is described by a nonlinear system of ordinary differential equations controlled by two inputs: the inlet concentration and the inlet temperature. We formulate the problem of maximizing the average product of this reactor for a fixed consumption of the input component over a period of time. This kind of isoperimetric optimal control problem is analyzed by using the Pontryagin maximum principle with Lagrange multipliers. We show that the optimal controls are bang-bang and propose an upper bound for the number of switchings for the linearized problem with periodic boundary conditions. Numerical simulations confirm that our control strategy can be used to improve the reactor performance over a specified period of time in comparison to the steady-state operation.

      PubDate: 2017-01-06T02:33:39Z
       
  • Covalent organic polymer modified TiO2 nanosheets as highly efficient
           photocatalysts for hydrogen generation
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Qingqing Yang, Peng Peng, Zhonghua Xiang
      Splitting water into hydrogen driven by solar energy is considered as one of the major strategies to provide clean energy. TiO2-based photo-catalysts have attracted everlasting interests due to low cost sources and excellent stability. However, the wide band gap and limited quantum efficiency of TiO2 hinder its application. Herein, a novel photocatalyst for hydrogen evolution was initially prepared by modification of TiO2 nanosheets with covalent organic polymer (i.e., COP-64). The COP-64 not only can provide more reaction active sites by increasing the specific surface area of the pristine TiO2 nanosheets, but also improve light harvesting in visible light region. Moreover, the suitable energy level of COP-64 provides charge transfer channels and favors the electron transfer, which greatly inhibits the combination of photogenerated electrons (e−) and holes (h+) in the hybrid system. Particularly, the corresponding hydrogen production rate of the hybrids reaches 15.02mmolh−1 g−1, which exceeds 63% compared with that of pristine TiO2 nanosheets (9.20mmolh−1 g−1).
      Graphical abstract image

      PubDate: 2017-01-06T02:33:39Z
       
  • Delta-operator-based adaptive model predictive control and online
           optimization of a natural gas liquefaction process
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Wangyun Won, Kwang Soon Lee
      The production of liquefied natural gas (LNG) is an energy-intensive process. The required temperature is approximately −160°C at atmospheric pressure. As a result, energy efficiency is the major concern in the process operation. Addressing this issue, we propose a new energy optimizing control system for the LNG process. It consists of an online steady-state optimizer, a model predictive controller (MPC), and a model parameter estimator. The optimizer computes optimum compression ratios and warm-end delta-temperature, while the MPC steers the process toward the target operating conditions. Particularly, the MPC was developed in a delta-form for better numerical stability during continuous operation of a multiple-input multiple-output system with widely distributed time constants. To minimize process perturbation by identification experiments, the model for controller design was derived from a rigorous LNG simulator. To cope with the model error from the true system, a small number of tunable parameters were introduced so that they can be corrected online by model parameter estimator during the process operation. The performance of the developed operation system was demonstrated in a numerical 100ton-per-day LNG plant, which was precisely constructed to replicate an actual plant in Incheon, Korea.

      PubDate: 2017-01-06T02:33:39Z
       
  • Effect of pressure drop model implemented for description of pressure drop
           on chromatographic monolith on estimated adsorbed layer thickness
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Miha Andrejčič, Aleš Podgornik
      Chromatographic monoliths are successfully implemented in many areas of separation science. Recently it was demonstrated that they can also be used for estimation of layer thickness formed by molecules adsorbed on surface of pores when pressure drop can be described by Kozeny-Carman model. This assumption is however questionable due to variety of monolith microstructures and high monolith porosity being regularly above 0.6. In this work proposed approach is extended to other pressure drop models for porosities between 0.60 and 0.95. It was demonstrated that estimated values of layer thickness with around 10% accuracy can be obtained in a broad porosity range regardless implemented pressure drop model. Therefore, no detailed information about monolith microstructure is needed to get reasonable estimation of thickness formed by adsorbed molecules.

      PubDate: 2017-01-06T02:33:39Z
       
  • Modeling an effect of pipe diameter on turbulent drag reduction
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Dmitry Eskin
      An effect of pipe diameter on drag reduction in a pipeline flow is taken into account by an adjustment of the modeling approach of Yang and Dou (2005). For validation of this adjustment, computational results obtained by the drag reduction models of Eskin (2014) and Yang and Dou (2010), based on the Yang and Dou approach, are compared with the experimental data of Virk (1975).

      PubDate: 2017-01-06T02:33:39Z
       
  • Simulation of microwave thin layer drying process by a new theoretical
           model
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Jun Jiang, Leping Dang, Cheong Yuensin, Hongsing Tan, Bochen Pan, Hongyuan Wei
      Various methodologies have been proposed in literature on modeling microwave drying process. However, in these methodologies moisture diffusion is normally considered in the presence of intensive microwave energy. In the present study, a new theoretical model was developed to simulate microwave drying of thin layer particulate solids, based on the consideration that moisture diffusion along material layer could be ignored due to rapid evaporation under intensive microwave energy. The model was solved numerically by using finite difference method and validated against experimental data. Results indicated good agreement between the model and experimental data, thus providing confidence in the modeling approach. For the system investigated in this study, it was demonstrated that an 80% reduction in drying time was achieved with approximately fivefold increase in microwave power (109–543W). Furthermore, it was also demonstrated that the drying rate was the maximum corresponding to the optimal layer thickness in microwave thin layer drying process. Qualitative analysis explained the optimal thickness phenomenon using principles of heat and mass transfer. Finally, the validated model was used to predict moisture and temperature distributions along the entire material layer.

      PubDate: 2017-01-06T02:33:39Z
       
  • Techno-economic analysis and environmental impact assessment of
           lignocellulosic lactic acid production
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Asfaw Gezae Daful, Johann F. Görgens
      Lignocellulosic Lactic acid (LA) production is considered for the diversification and value addition to an existing sugar industry by annexing a biorefinery using lignocellulosic residues, sugarcane bagasse and leaves (SCBL). In biorefinery, the hemicellulose (C5 sugars) and cellulose (C6 sugars), resulting from lignocellulosic matrix fractionation, can be converted into building block chemicals and fuels by biotechnological or chemical pathways. To co-produce LA with other fuels and chemicals from SCBL, it is important to determine whether LA production from C5 or C6 sugars should be preferred, based on economic viability and environmental impacts. In this paper we developed six process scenarios for LA production from either the hemicellulose liquid fraction and cellu-lignin solid fractions of SCBL after steam explosion pretreatment, based on 200tonne/day of SCBL feed. The lignocellulose fraction not used for LA production will be used for integrated production of other marketable products in a biorefinery. Scenarios S1, S3, & S5 use the hemicellulose liquid fraction as feed for LA production, while scenarios S2, S4, & S6 use the cellu-lignin solid fraction. Two scenarios, S1 & S2, use Ca(OH)2 as neutralizer in fermentation, resulting in co-production of gypsum as solid waste, scenarios S3 and S4 use an isolated acid-tolerant thermophilic bacteria, Bacillus coagulans isolates for fermentation, thus avoiding the need for neutralization, while Scenarios S5 and S6 use Mg(OH)2 as neutralizer in fermentation, with recycling of Mg(OH)2. LA was separated and purified from the fermentation broth by reactive distillation. The six process scenarios were modeled and simulated by Aspen Plus® with the resulting mass & energy balance and equipment-sizing used as inputs to economic analysis and environmental impact assessment. Standard life cycle assessment (LCA) method is used in SimaPro® for environmental impact quantification. Cellulose based processes have larger LA production rates than the hemicellulose based processes, for the same flow rate of SCBL, which impacts on their total capital investment (TCI), operating cost (OPEX) and revenues for the same process technology. Increases of 7.08%, 58.13%, 12.04% and 60% in TCI, revenue, OPEX and LA production rates, respectively were observed in moving from S1 to S2. Similar increases of 10.88%, 86.52%, 18.52% and 91.07% in TCI, revenue, OPEX and LA production respectively in moving from S3 to S4. An increment of 10.08%, 61.57%, 18.32% and 63.90% in TCI, revenue, OPEX and LA production respectively was also found in moving from S5 to S6. Scenarios S3 and S4 are found to have lower TCI and OPEX but their production rate is low as well making them economically less attractive with internal rate of return (IRR) of 9.13% and 15.23% respectively. While S1 and S2 have IRR of 13.11% and 19.4% respectively and yet higher TCI and OPEX. S5 and S6 have the highest IRR, 14.72% and 21.28% respectively with TCI and OPEX of way below their equivalent scenarios S1 and S2 respectively. From the environmental point of view S1 and S2 are found to be environmentally less friendly with higher environmental burdens in almost all impact categories considered. Gypsum free scenarios, S5 and S6, are found to be the most attractive processes from both economic and environmental points of view, with S6 being superior than S5.

      PubDate: 2017-01-06T02:33:39Z
       
  • Theoretical analysis of the influence of forced and inherent temperature
           fluctuations in an adiabatic chromatographic column
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Shamsul Qamar, Fouzia Abdul Sattar, Iqra Batool, Andreas Seidel-Morgenstern
      A linearized non-isothermal equilibrium dispersive model (EDM) of liquid chromatography is investigated to quantify unavoidable thermal effects in adiabatic chromatographic columns. The considered model contains convection-diffusion partial differential equations (PDEs) for mass and energy balances in the mobile phase coupled with an algebraic equation for adsorption isotherm. The solution process successively employ Laplace transformation and linear transformation steps to uncouple the governing set of coupled differential equations. The resulting uncoupled systems of ordinary differential equations are solved using an elementary solution technique. The solutions are very useful to understand the speeds and shapes of concentration and thermal fronts in chromatographic columns. The moment generating property of the Laplace domain solutions is utilized to derive analytical temporal moments of the concentration and temperature profiles. These moments are seen as useful to estimate unknown model parameters from measured profiles. For illustration several case studies of practical interest are provided. To evaluate the range of applicability of analytical solutions, selected results are compared with numerical results applying a high resolution finite volume scheme considering nonlinear isotherms.

      PubDate: 2017-01-06T02:33:39Z
       
  • Catalytic hydrothermal liquefaction for bio-oil production over CNTs
           supported metal catalysts
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Yu Chen, Rentao Mu, Mingde Yang, Lina Fang, Yulong Wu, Kejing Wu, Ya Liu, Jinlong Gong
      This paper describes catalytic consequence of hydrothermal liquefaction (HTL) of Dunaliella tertiolecta (D. tertiolecta) over carbon nanotubes (CNTs) supported metals catalysts to produce bio-oil. When Co/CNTs is used as catalysts, the conversion and bio-oil yield increase to 95.78 and 40.25wt.%, respectively. Chemical analysis results showed that the introduction of catalyst significantly affected the chemical composition of bio-oil with a higher percentage of hydrocarbons and a lower content of fatty acid. The introduction of metal into CNTs had no change in the basic CNT skeleton and the loaded metal nanoparticles encapsulated within the CNT enhances the disorder and defects in CNTs. Based on our results and the literature, the plausible general reaction and catalytic HTL pathways of D. tertiolecta are proposed.
      Graphical abstract image

      PubDate: 2017-01-06T02:33:39Z
       
  • Analysis of interaction between bubbles and particles in a dense gas-vibro
           fluidized bed
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Liang Dong, Enhui Zhou, Liping Peng, Chenlong Duan, Yuemin Zhao, Zhenfu Luo, Qingxia Liu
      Gas-solid fluidized beds are widely used for their excellent characteristics of heat and mass transfer. An active pulsating air flow is introduced into a dense gas-solid fluidized bed, forming a dense gas-vibro fluidized bed (DGVFB), to modify the fluidization quality. Interaction between the bubbles and particles in the DGVFB was investigated based on the results of numerical simulations and experiments. Micro-bubbles in the DGVFB were regarded as springs, and therefore, the interaction between the bubbles and particles was considered to be equivalent to a linear vibration system with n degrees of freedom. A dynamic model for the vibration system was developed, and modal analysis was conducted. Results of this theoretical analysis showed that the dominant frequency of pressure fluctuations in the DGVFB was equal to the frequency of active pulsating air flow. The dynamic model described the interaction between the bubbles and particles effectively in the DGVFB at low gas pulsating frequency, and shallow fluidized beds.

      PubDate: 2017-01-06T02:33:39Z
       
  • Bubble movement in a rotating eddy: The implications for particle-bubble
           detachment
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Guichao Wang, Geoffrey M. Evans, Graeme J. Jameson
      Bubbles are an essential part of the froth flotation process for the separation of mineral particles. However, little information is available on the behaviour of bubbles in the turbulent flows in a flotation machine. It has been noted in flotation kinetics studies that the behaviour of bubbles in turbulent eddies is a significant factor in bubble-particle collision, attachment and detachments. In this paper, the performance of single bubbles and groups of bubbles inside a rotating eddy have been studied experimentally. Bubbles were released into a turbulent rotating field in a wall cavity, where a confined eddy was developed by controlling the water flow into the water channel over the open mouth of the wall cavity. To study the behaviour of particles attached to bubbles in the turbulent eddies, particle-bubble aggregates were generated in an external fluidized bed and introduced into the rotating eddy with no frothers added. The process of particle detachment due to centrifugal movement was captured by a high-speed camera. The traditional theory of particle-bubble detachment, which assumes a centrifugal motion of the attached particle on the surface of the bubble, was experimentally verified. However, other modes were also observed. For example, bubbles carrying particles can be brought together in a turbulent vortex, resulting in bubble coalescence and consequent detachment of particles. Inertial detachment modes are also seen, due to rapid changes in the trajectory of the bubble, or because of oscillations of the bubble’s surface.

      PubDate: 2017-01-06T02:33:39Z
       
  • Transport-reaction-permeation regimes in catalytic membrane reactors for
           hydrogen production. The steam reforming of methane as a case study
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): M.A. Murmura, S. Cerbelli, M.C. Annesini
      Catalytic reactors equipped with dense metallic membranes for hydrogen production are attracting increasing interest in view of their potential to overcome yield limitations associated with chemical equilibrium. A transport-reaction-permeation isothermal model, fully coupled with momentum transport through the packed bed, is here considegd for the species participating to the methane steam-reforming reaction in an annular catalytic reactor fed by a pre-reformed (equilibrium) mixture. Model predictions are validated by comparison with experimental data available in the literature. Large variations of the mixture density are found as a consequence of nonuniform composition profiles, which, in turn, trigger sizeable radial convective fluxes of hydrogen towards the membrane. Nonlinearities associated with chemical equilibrium, reaction kinetics, membrane permeation, and density dependence on composition interact with one another, making the overall equipment response markedly complex. A thorough dimensionless analysis of the response of the reactor vs the operating pressure is carried out, which shows the occurrence of non-monotonic behavior characterized by a maximum of efficiency associated with a critical pressure value. A scaling law of critical efficiency vs the main dimensionless parameters is proposed, which can provide a rationale for the design of reactor geometry and operating conditions.

      PubDate: 2017-01-06T02:33:39Z
       
  • Analysis of solubility, absorption heat and kinetics of CO2 absorption
           into 1-(2-hydroxyethyl)pyrrolidine solvent
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Helei Liu, Moxia Li, Raphael Idem, Paitoon (PT) Tontiwachwuthikul, Zhiwu Liang
      The CO2 absorption performance of aqueous 1-(2-hydroxyethyl)pyrrolidine (1-(2-HE)PRLD) was studied with respect to kinetics (i.e., in terms of the pseudo-first-order rate constant (k o) and second-order reaction rate constant (k 2), obtained using the stopped-flow apparatus). CO2 equilibrium solubility and heat of CO2 absorption were evaluated at the temperature range of 293–313K in the 1-(2-HE)PRLD concentration range of 0.20–1.00mol/L for kinetics and at 2M for CO2 solubility. The values of k o were then represented using the base-catalyzed hydration mechanism, which gave an acceptable AAD of 10%. In addition, Brønsted plots of k 2 vs. pKa were developed to predict k 2 using pKa values of various tertiary amines. In addition, the CO2 equilibrium solubility and CO2 absorption heat were obtained in this work. Based on a comparison with other amines such as MEA, MDEA and 1DMA2P, 1-(2-HE)PRLD showed better performance in terms of CO2 equilibrium solubility (DEAB>1-(2-HE)PRLD>1-(2HE)PP>1DMA2P>MDEA>MEA>DEA), kinetics (MEA>DEA>DEAB>1-(2-HE)PRLD>1-(2-HE)PP>DMMEA>1DMA2P>MDEA.) and CO2 absorption heat (MEA>DEA>MDEA>DEAB>1-(2-HE)PRLD>1-(2HE)PP>1DMA2P). Therefore, 1-(2-HE)PRLD could be considered as a good alternative solvent for CO2 capture. A correlation between kinetics and heat of CO2 absorption has been developed to guide the design of what can be considered to be ideal amine solvents for CO2 capture.

      PubDate: 2017-01-06T02:33:39Z
       
  • Modeling of multiphase reaction and slag flow in single-burner coal water
           slurry gasifier
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Jianliang Xu, Zhenghua Dai, Haifeng Liu, Liangyu Guo, Feng Sun
      The slag flow properties and temperature distribution have a critical influence on the lifetime of refractory bricks. A comprehensive model has been developed to simulate a multiphase flow and reaction process within the spatial region and refractory wall, and is applied to a study on the multiphase flow characteristics of a single-burner entrained-flow gasifier. The gasifier performance, gas temperature distribution, and outer surface temperature distribution of the wall are compared with industry measurement data. The simulation results are in good agreement with the industrial data. The capture efficiency of the refractory wall is approximately 91%, and 82% of the particles are trapped by the wall. The distribution of the gas temperature near the refractory wall, the slag surface temperature, and the refractory wall surface temperature aresimilar. The slag surface temperature first decreases from top to bottom, and then increases to the highest temperature at 2.2D. The slag attack rate coincides with the refractory brick corrosion rate. The refractory surface temperature, molten slag fluidity, and molten slag flow rate have a significant impact on the refractory brick corrosion rate. No solid slag layer is present on the refractory bricks, and the molten slag layer thickness increases from 0 to 5mm along the flow direction. In the molten slag layer, the non-dimensional slag velocity profile shows a self-similarity and follows a parabolic equation.

      PubDate: 2017-01-06T02:33:39Z
       
  • Modeling of a tubular solar reactor for continuous reduction of CeO2: The
           effect of particle size and loading on radiative heat transfer and
           conversion
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): P.J. Valades-Pelayo, H.I. Villafán-Vidales, H. Romero-Paredes, C.A. Arancibia-Bulnes
      A solar multi-tubular reactor for non-stoichiometric reduction of CeO2 is modeled under continuous operation. An aerosol, consisting on CeO2 particles and Argon, flows upwards through the reactor vertical tubes. Heat, mass and radiation transfer phenomena are efficiently implemented in an axisymmetric domain by using multi-mesh, multi-step, Finite-Volume and Monte Carlo methods. Reaction, particle diffusion, conduction, forced convection as well as radiation absorption, emission and anisotropic scattering are considered. The kinetic model for the non-stoichiometric reduction of CeO2 is taken from Ishida et al. (2014). Model results at steady-state focus on the effect of changing particle loading and diameter at different average residence times. For particle diameters of 1–20μm, increasing particle size favors uniform radiation absorption, minimizing temperature gradients. Finally, for an outer tube surface temperature of 2500K, a particle loading of 0.1kg/m3 and average residence time of 30–60s are recommended.

      PubDate: 2017-01-06T02:33:39Z
       
  • Experimental study of particle evolution characteristics in an opposed
           multi-burner gasifier
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Qing Zhang, Yan Gong, Qinghua Guo, Zhicun Xue, Fuchen Wang, Guangsuo Yu
      Based on a bench-scale opposed multi-burner (OMB) gasifier and advanced visualization techniques, the particle evolution characteristics in the gasifier was studied. Particle images of different focusing planes were obtained by optical sectioning tomography (OST) method. Particle types and the principles of transformation between them, particle shape and particle size distribution (PSD), particle fragmentation characteristics were statistically analyzed after image processing. The results show that the burner plane contains all of the particle types, most of them are high temperature particle without wake (HTP), low temperature particle without wake (LTP), high temperature particle with high temperature wake (HTP-HTW) and low temperature particle with high temperature wake (LTP-HTW). Particle shapes in the burner plane are mainly round or round-like. The particle fragmentation process in the burner plane is violent and usually accompanied by sudden bursts that would result in the change of particle motion status, but the probability of which is relatively low (only about 7%). The space between 100mm and 300mm above the burner plane is the main regions of particle pyrolysis, particle types are mainly the low temperature particle with low temperature wake (LTP-LTW). Particles at 100mm above the burner plane have a higher fragmentation probability (10.53%) than that at 200mm (9.51%) and 300mm (8.73%) above the burner plane because of the more intense pyrolysis. In these regions, particle shapes become more irregular and the median particle diameter (D50) are slightly increased. There are plenty of LTP in the space between 400mm above the burner plane to the refractory dome. The probability of fragmentation around 400mm (16.84%), 500mm (11.35%) and 580mm (9.32%) above the burner plane are all higher than the probability around 100mm, 200mm and 300mm above the burner plane, which indicates that the particle fragmentation has more probability to take place in the char gasification stage than in the pyrolysis stage in the OMB gasifier. The closer to the refractory dome, the less the number of large particle is and the smaller the D50 is. About 85% of the particles near the refractory dome have a diameter less than 500μm.

      PubDate: 2017-01-06T02:33:39Z
       
  • Extrapolation of surface tensions of electrolyte and associating mixtures
           solutions
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Hailong Chen, Zhaomin Li, Fei Wang, Zhuangzhuang Wang, Gao Zhihan
      A new surface tension model is proposed, based on the Gibbs phenomenological surface-phase method, coupled with Ion-based Statistical Associating Fluid Theory (Ion-based SAFT2). The model was used to extrapolate the surface tensions of aqueous electrolyte solutions and mixed electrolyte solutions, as well as systems of associating mixtures at different temperatures and concentrations, and was found to give good agreement with experimental data from the literature.

      PubDate: 2017-01-06T02:33:39Z
       
  • Liquid-like granular film from granular jet impact
    • Abstract: Publication date: 27 April 2017
      Source:Chemical Engineering Science, Volume 162
      Author(s): Zhe-Hang Shi, Wei-Feng Li, Wen-Wei Qian, Hai-Feng Liu, Fu-Chen Wang
      Dynamic behaviors of dense granular jets impacting a flat target are experimentally studied and numerically simulated using the Discrete Element Method. Effects of the granular jet velocity (u 0 ⩽6.5m/s), the particle diameter (82⩽ d ⩽350μm), the jet diameter (1⩽ D ⩽12mm), and the volumetric solid content ratio of the granular jet (0.05⩽ x p <0.62) on the flow patterns are investigated. Two patterns were identified: the thin, liquid-like granular film and the diffuse pattern. The profile and thickness of granular films have been characterized. The transition critical parameters and maps of the two patterns are obtained in this work. Results show that the regimes of the granular jet impact are primarily determined by the ratio of jet diameter to particle diameter (D/d) and solid content ratio (x p). A compacted dead zone over the target forms with large D/d and x p, which subsequently causes rapid interparticle inelastic collisions and circular motion of the granular film.
      Graphical abstract image

      PubDate: 2017-01-06T02:33:39Z
       
  • On the effect of surfactants on drop coalescence at liquid/liquid
           interfaces
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Weheliye Hashi Weheliye, Teng Dong, Panagiota Angeli
      In this work the effect of surfactants on the coalescence of a drop with a flat aqueous-organic interface was experimentally investigated. A high speed Particle Image Velocimetry (PIV) system was used to obtain velocity profiles and kinetic energy per unit mass distribution inside the coalescing droplets. Different mass ratios of surfactant to oil below the CMC value, up to ϕ =5×10−4, of a non-ionic surfactant dissolved in the organic phase were studied. It was found that an increase in the surfactant concentration promoted the deformation of the interface before the film that separated the drop from the interface ruptured. A high surfactant concentration also increased the time needed for film rupture. When rupture occurred, two counter-rotating vortices formed inside the droplet on either side of the rupture point, which moved upwards with time. The propagation of the vortices inside the droplet was faster for low surfactant concentrations, while the intensities of the two counter-rotating vortices significantly decreased for increasing surfactant concentration. At the early stages of coalescence after film rupture, the kinetic energy per unit mass was mainly distributed near the bottom part of the droplet, while at later stages it was distributed near the upper part of the droplet.

      PubDate: 2017-01-06T02:33:39Z
       
  • Study the effect of dense internals on the liquid velocity field and
           turbulent parameters in bubble column for Fischer–Tropsch (FT) synthesis
           by using Radioactive Particle Tracking (RPT) technique
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Mohammed K. Al Mesfer, Abbas J. Sultan, Muthanna H. Al-Dahhan
      In this study, the effects of the dense vertical internals on the liquid velocity field and turbulence parameters (Reynolds stresses, turbulent kinetic energy, and turbulent eddy diffusivities) are experimentally investigated for the first time by using advanced Radioactive Particle Tracking (RPT) technique. The experimental work was carried out in a Plexiglas bubble column with 5.5in. (0.14m) and a height of 72in. (1.83m) for the air-water system. In this work, thirty vertical Plexiglass internals of 0.5in. (0.0127m) outer diameter were used which covered ∼25% (typical for Fischer–Tropsch processes) of the total cross-sectional area of the column where they arranged as the triangular pitch of 0.84in. (0.0214m). The superficial gas velocities based on both total cross-sectional area and free cross-sectional area available for the flow were utilized (0.08, 0.2, and 0.45m/s), which covered the transition and churn-turbulent flow regime to meet the industrial applications of FT synthesis. The experimental data show that the presence of the internals at a given superficial gas velocity causes an increase in the axial centerline liquid velocity and a sharp decrease in turbulence parameters while the increase in superficial gas velocity in the presence of internals causes an increase in axial centerline liquid velocity and turbulent parameters. The obtained data are reliable as a benchmark data for validation computational fluid dynamics (CFD) simulation, and models.

      PubDate: 2017-01-06T02:33:39Z
       
  • Population balance of droplets in a pulsed disc and doughnut column with
           wettable internals
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Qi Fang, Dian Jing, Hao Zhou, Shaowei Li
      Population balance of droplets was studied in a square-sectioned pulsed disc and doughnut column with wettable internals. It was found that a liquid film of the dispersed phase was formed on the internals. To describe the interaction between the droplets and the liquid film, three more terms need to be added into the source term of the classic population balance equation (PBE). To determine the source term of the PBE, functions including the droplet-layer coalescence frequency, residual droplet size distribution, droplet dispersion frequency from the liquid layer, droplet breakup frequency, and daughter droplet size distribution were measured experimentally. The droplet-layer coalescence frequency increases as the pulsation intensity decreases because of the longer contacting time. The residual droplet size is around half of the original coalescing droplet and affected little by the pulsation. The droplet dispersion frequency gets higher with the increasing of the pulsation intensity or the thickness of the liquid layer. The droplet breakup frequency is positively related to the energy input and droplet size. The daughter droplet size distribution changes from inverted U-shaped to M-shaped as the pulsation intensity rises. Based on the experimental results, empirical correlations were proposed to calculate these functions. Furthermore, the correlation equations were applied in a simplified population balance model to calculate the droplet number density in the column. The predicted results agree well with the experimental data, which proved the feasibility of the correlations.

      PubDate: 2017-01-06T02:33:39Z
       
  • Water film rupture in blocked oil recovery by gas injection: Experimental
           and modeling study
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Seyedamir Mirazimi, Behzad Rostami, Mohammad-Hossein Ghazanfari, Maryam Khosravi
      Water shielding phenomenon generally occurs after waterflooding in water-wet rocks, and impedes direct contact between the oil and the injected gas in tertiary gas injection processes. In this work, a set of visualization experiments were performed on micromodel patterns including designed dead-end pores with a film of water on the surface of pore bodies, which is a more realistic representation of porous media. The experiments were conducted at different miscibility conditions, and the required time for water to be displaced from the throat by the swelling of oil was measured for first contact miscible (n-C5/CO2) and immiscible (n-C10/CO2) systems. In the next step, a model was proposed to simulate the results of the experiments, based on the work of Bijeljic et al. (2003). As the impact of non-ideal mixing in this process has not been previously discussed in the available literature, the new model was developed by taking into account the changes in the partial molar volumes of oil and gas components using the PR and the SRK equations of state, and also by considering the mass transfer from the surrounding water on the pore body into the shielded oil. The rupture times predicted by the model were compared with the measured experimental data, as well as those reported by Campbell and Orr (1985). It was found that inclusion of partial molar volumes of components improves the accuracy of the model. The results also revealed the significant role of the water film on the pore body surfaces in mass transfer rate between the phases in water-wet media. The close agreement between the results of the model proposed in this study and the experimental data shows that it can be helpful for developing more accurate multiphase compositional models.
      Graphical abstract image

      PubDate: 2017-01-06T02:33:39Z
       
  • Mass transfer between bubbles and seawater
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Jan Erik Olsen, Dorien Dunnebier, Emlyn Davies, Paal Skjetne, John Morud
      Mass transfer between bubbles and seawater is an important mechanism when determining how much gas reaches the atmosphere from gas sources at the seabed. The mass transfer coefficient is a governing parameter for the phenomenon. Experiments on small bubbles in seawater have been performed where the bubble size has been monitored. The observed evolution of the bubble size has been compared with theoretical predictions of the bubble size. Based on this comparison, it is shown that mass transfer correlations for contaminated conditions is more consistent with experiments than correlations for clean conditions. It is also learned that simultaneous desorption of gases dissolved in the liquid must be accounted for.

      PubDate: 2017-01-06T02:33:39Z
       
  • A kinetic model of one-pot rapid biotransformation of cellobiose from
           sucrose catalyzed by three thermophilic enzymes
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Chao Zhong, Ping Wei, Yi-Heng Percival Zhang
      Cellobiose is a zero-calorie functional sweetener and a potential healthy food/feed additive. Current production methods of cellobiose from high-purity cellulose always suffer from low product yields and high separation costs. Here one-pot biotransformation composed of three thermophilic enzymes sucrose phosphorylase (SP) from Thermoanaerobacterium thermosaccharolyticum, glucose isomerase (GI) from Streptomyces murinus, and cellobiose phosphorylase (CBP) from Clostridium thermocellum was designed to convert sucrose to cellobiose. To reveal the underlying relationship within the three enzymes and optimize reaction conditions, a kinetic model was developed. Model simulation predicted the optimal SP:GI:CBP enzyme loading ratio in terms of enzyme unit was 0.5:1.0:1.5. The enzyme cocktail with the optimal ratio converted 100mM sucrose to 62.3mM cellobiose within 10h. Model simulation also found out that the optimal phosphate concentration was approximately 10.3mM for 100mM sucrose, which was validated by experimental data. This study could assist the sugar industry to diversify the production of new value-added products from sucrose.
      Graphical abstract image

      PubDate: 2016-12-27T13:31:35Z
       
  • Breakage of fractal agglomerates
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Xiaoliang Deng, Rajesh N. Davé
      Breakage behavior of fractal agglomerates as a function of impact velocity and surface energy was investigated using discrete element method (DEM). Agglomerates with fractal dimensions (Df ) ranging from about 2.0 to 2.8 were produced by letting primary particles having random initial velocities agglomerate under a centripetal force. The simulation results show that the damage ratio (Dm ), defined as the ratio of broken interparticle contacts to the initial total contacts, decreases with increasing fractal dimension in the range between 2.0 and 2.6, which can be explained by the increased mechanical strength with increasing fractal dimension. Previously introduced Weber number (We) based correlation for damage ratio is generalized by incorporating the fractal dimension: D m = B W e D f 2 α , where B and α depend exponentially and linearly on Weber number, respectively. Visualization of impact process illustrates the feature of ductile fracture of fractal agglomerates irrespective of fractal dimensions.
      Graphical abstract image

      PubDate: 2016-12-27T13:31:35Z
       
  • DEM-CFD investigation of particle residence time distribution in top-spray
           fluidised bed granulation
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Matthias Börner, Andreas Bück, Evangelos Tsotsas
      Numerical simulations in process engineering become more and more to a powerful tool in process optimisation and for improvement of process understanding. For multiphase flows, like fluidised bed granulation as a three phase system, the dynamics can be described by the coupled approach between the Discrete Element Method (DEM) for the solid and liquid phase with Computation Fluid Dynamics (CFD) for the gas phase. A key challenge in this simulation approach is given by the huge number of single particles in the original system. In order to run a three-phase top-spray fluidised bed by the coupled DEM-CFD in reasonable time scales, a scaling approach based on similarity models has been applied. Within the top-spray fluidised bed particle and droplet motions are investigated in a two-compartment approach, considering a spray and a drying zone. It can be shown that different particle crossing lengths and particle velocities through the spray zone lead to a particle residence time distribution with crucial impact on particle wetting and thus growth behaviour. In addition top-sprayed droplets are respected to obtain droplet existing time distributions and therefrom overspray ratios. Concluding from the results different particle wetting procedures in the spray zone are identified and discussed.
      Graphical abstract image

      PubDate: 2016-12-27T13:31:35Z
       
  • Kinetic modelling of the hematin catalysed decolourization of Orange II
           solutions
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Cecilia Cabrera, Andrés Cornaglia, Agostina Córdoba, Ivana Magario, María Lujan Ferreira
      A mathematical description of the kinetics of the hematin catalysed decolourization reaction of Orange II alkaline solutions was constructed and validated under the assumption that hematin mimics the action of peroxidases. The clean oxidant H2O2 was applied, however, hematin dismutated it, as catalases do, under reaction conditions. Thus, special attention was cared to the understanding of this ineffective side-reaction by the proposal of straightforward pathways concerning the catalatic or the pseudo-catalatic cycles. Model validations were implemented by a parametrization procedure of relevant rate constants under dynamic simulation fitting to selected experimental time-courses data. The peroxidatic coupled to pseudo-catalatic mechanism gave predictions closer to experimental findings in a wide range of conditions. The initial rate method for data processing was successfully applied for providing reliable initial rate constant guesses but also for the detection of unexpected rate depletion at high dye concentrations. This was considered in the model as unproductive dye coordination to hematin native state prior to H2O2 activation. The pseudo-catalatic pathway involves the production of superoxide and its coordination to hematin native state to afford inactive but regenerable ferrous porphyrin. Model underestimations of experimental data were interpreted as cooperative oxidation of Orange II molecules by superoxide whereas model deviations at high dye concentration (>400mg/l) was assigned to further hematin catalysed oxidation of Orange II degraded products.
      Graphical abstract image

      PubDate: 2016-12-27T13:31:35Z
       
  • Parameter estimation and analysis of an automotive heavy-duty SCR catalyst
           model
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Andreas Åberg, Anders Widd, Jens Abildskov, Jakob Kjøbsted Huusom
      A single channel model for a heavy-duty SCR catalyst was derived based on first principles. The model considered heat and mass transfer between the channel gas phase and the wash coat phase. The parameters of the kinetic model were estimated using bench-scale monolith isothermal data. Validation was done by simulating the output from a full-scale SCR monolith that was treating real engine gases from the European Transient Cycle (ETC). Three simplified models were derived, with simplifications that substantially decreased simulation time. These simplified models were coupled with the kinetic model and parameters of the nominal model, and their predictive performances were compared. Based on the results, two of the models were chosen for recalibration of the kinetic parameters, and analysed again. The results show that, after recalibration, the model that included simplifications related to mass transfer was able to keep most of its predictive capabilities, while the simulation time was reduced substantially.

      PubDate: 2016-12-27T13:31:35Z
       
  • Reaction kinetics of carbon dioxide and hydroxide in aqueous glycerol
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Di Song, Gary T. Rochelle
      The reaction kinetics of carbon dioxide and sodium hydroxide (nominally 0.1N and 0.3N) in aqueous glycerol were measured in a wetted wall column (WWC) at 20, 30, and 40°C. Glycerol was added at 0–89wt% to achieve a liquid viscosity (μL ) of 0.89–65cP. Compared to pure aqueous alkaline solution, the absorption rate (kg ′) initially increased by 30% and then decreased rapidly by 75% with increasing glycerol. Based on the measured kg ′, a model was developed to calculate the overall reaction rate constant (k Alk), which resulted from the competing effects of CO2/NaOH ( k OH - ) and CO2/glyceroxide ( k Glycerol - ) reactions. The k Glycerol - was 6–7 times faster than k OH - . The non-monotonic trend of kg ′ was the combined effect of k Alk increasing and diffusivity (D CO2) decreasing when glycerol increased. The effect of alkalinity depletion at the gas/liquid interface has been included in the kinetic model. The average depletion for 0.1N NaOH is 4% for water and 20% for 89wt% glycerol. Average depletion was less than 3% for 0.3N NaOH. The addition of 0.05N sodium carbonate has an insignificant effect on kg ′.

      PubDate: 2016-12-27T13:31:35Z
       
  • A probabilistic approach to modeling struvite precipitation with uncertain
           equilibrium parameters
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): N.J. Barnes, A.R. Bowers
      The precipitation and accumulation of struvite ( MgNH 4 PO 4 · 6 H 2 O ) within anaerobic processes has been a costly problem for wastewater facilities. To anticipate and mitigate struvite buildup, solubility models have been developed that employ equilibria software for the evaluation of equilibrium equations. Unfortunately, these programs run under the assumption that chemical equilibrium constants are single, universally accepted values when, in reality, a wide range of values have been published for these constants. In this study, a struvite solubility model was developed in which the equilibrium constants were treated as empirically distributed variables within a Monte Carlo simulation to understand the effect of uncertainty on precipitation potential over a range of pH (6–8.5), temperature (0–60°C), and ionic strength (0–1M). Using field conditions measured at a struvite-afflicted treatment plant as model input parameters, the resulting uncertainty in the struvite supersaturation ratio was found to be highly consequential, with the 90 percent confidence interval spanning well over an order of magnitude. Additionally, a sensitivity analysis was performed on the model, identifying the third orthophosphate equilibrium constant and the struvite solubility product as the most significant source of uncertainty.

      PubDate: 2016-12-27T13:31:35Z
       
  • Prediction of gas–liquid flow in an annular gap bubble column using a
           bi-dispersed Eulerian model
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Gaël Raymond Guédon, Giorgio Besagni, Fabio Inzoli
      We present and discuss numerical results from simulations of the air–water flow in an annular gap bubble column of 0.24m internal diameter, at air superficial velocities ranging from 0.004 m/s to 0.225 m/s, covering the homogeneous and heterogeneous flow regimes. A bi-dispersed Eulerian model is implemented to account for both the stabilizing and destabilizing effects of small and large bubbles. Sensitivity studies on the mesh element size, time step size and number of outer iterations per time step are performed and most appropriate simulation parameters and mesh are used to predict the gas holdup curve. Comparison with two mono-dispersed models is provided to emphasize the necessity of a bi-dispersed approach for the accurate prediction of the homogeneous flow regime, given the poly-dispersed nature of the flow investigated. Two different approaches for the characterization of the small and large bubbles groups are also discussed. We found that the relative amount of small bubbles is an important input parameter for the present model and can be provided using available empirical correlations or experimental data. The results obtained from the simulations also demonstrated the necessity of a population balance model able to capture the bubbles coalescence and breakup phenomena for the correct prediction of the heterogeneous flow regime.
      Graphical abstract image

      PubDate: 2016-12-27T13:31:35Z
       
  • A DEM-based approach for analyzing energy transitions in granular and
           particle-fluid flows
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Q.F. Hou, S.B. Kuang, A.B. Yu
      Granular and particle-fluid flows are widely observed in nature and in industry. Their behaviors are determined by the injection of energy and the subsequent cascade of energy. This work presents a DEM-based approach for the analysis of energy transitions in such flows. The approach can consider the energy injection, dissipation and conversion due to driving forces such as particle-fluid interactions and the gravitational force, particle-particle/wall collisions and frictions. The effectiveness is demonstrated in two systems respectively and the transient and averaged energy transitions are discussed. The results reveal the connection between the formation of a cluster and the variation of energy in fluidized beds. From the viewpoint of energy transition, the results also illustrate the minimization of energy dissipation, the startup of fluidization and the particle flow distribution. Furthermore, the correlation of the contact between particles and the energy transition is demonstrated. The findings should be useful for the understanding of structure formation in fluidized beds and for industrial applications.

      PubDate: 2016-12-19T18:22:31Z
       
  • Impact of relative humidity on a nanostructured filter cake –
           Experimental and modelling approaches
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Q. Ribeyre, A. Charvet, C. Vallières, D. Thomas
      In this paper, three different non-hygroscopic nanostructured powders were dispersed in dry air and filtered to create a nanostructured deposit. The relative humidity was then gradually increased from 0 to 85% and the thickness of the deposit continuously measured using a laser trigonometry device. Experimental results showed that for each sample, the pressure drop of the deposit increases when the relative humidity increases, while the bed thickness decreases. The modelling of the pressure drop upon increasing humidity was conducted using two pressure drop models available in the literature and specifically developed for nanostructured deposits. The variations in porosity and in cake thickness were included in the pressure drop models. This was achieved using a semi-predictive model of adsorption-condensation on nanoparticle beds developed to calculate the water mass sorbed by a powder. The modified models represent the experimental results with a maximum deviation of 10%.

      PubDate: 2016-12-19T18:22:31Z
       
  • Elucidating the role of ammonia-based salts on the preparation of
           cellulose-derived carbon aerogels
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Luis E. Arteaga-Pérez, Oscar Gómez Cápiro, Aaron M. Delgado, Serguei Alejandro Martín, Romel Jiménez
      The effects of using (NH4)2SO4 as a carbonization promoter for producing cellulose-derived carbon aerogels (CAG) was studied. The effects of pretreatment on the textural, morphological, and chemical properties of pristine cellulose nanofibers (CNF) were analyzed through N2 adsorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), elemental analysis, inductively coupled plasma optical emission spectrometry (ICP-OES), and Fourier transform infrared spectroscopy (FT-IR). Furthermore, the thermal behaviors of raw CNF and those impregnated with (NH4)2SO4 were investigated by coupling thermogravimetric analysis with mass spectrometry (TGA-MS). The results suggested that the pretreatment did not cause any morphological/structural changes in the nanofibers. However, the presence of (NH4)2SO4 affected their pyrolysis by favoring intermolecular dehydration, thereby reducing the formation of levoglucosan and increasing the carbon yield during pyrolysis. Interestingly, above certain impregnation level, the concentration of sulfate-derived species in the gas phase increased. This phenomenon was attributed to an excess of salt within the fiber structure and on their surfaces. Consequently, the levoglucosan-to-carbon route was inhibited, and the mechanisms of intra- and inter-molecular dehydration, chain scission, and crosslinking reactions were affected, leading to a reduced char yield. The chemical effects of ammonia-based salts is elucidated supported on the interpretation of MS signals and kinetic modeling results.

      PubDate: 2016-12-19T18:22:31Z
       
  • CFD study on thermal transport in open-cell metal foams with and without a
           washcoat: Effective thermal conductivity and gas-solid interfacial heat
           transfer
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Wenping Peng, Min Xu, Xunfeng Li, Xiulan Huai, Zhigang Liu, Huasheng Wang
      Metal foams are considered to be attractive catalyst carriers for strongly exothermic/endothermic catalytic processes, but the washcoat may have a significant influence on the thermal transport properties of the metal foams. In this work, the effective thermal conductivity and the gas-solid interfacial heat transfer of coated metal foams were studied using a periodic unit cell model in the CFD method. We emphasizedanalysing the effect of the washcoat on the effective thermal conductivity, pressure drop and interfacial heat transfer of metal foams. The results indicated that the influence of the washcoat on the effective thermal conductivity depends on the conductivity in three phases. A large deviation was found when we used the available empirical correlations for metal foams to predict the effective thermal conductivity of the coated metal foams. A correlation for the effective thermal conductivity of coated metal foams was proposed by considering the washcoat as a separate phase. With increasing washcoat thickness, it was found that the pressure drop increases but the gas-solid interfacial heat transfer decreases. Moreover, we verified the enhancement of viscous flow within the washcoat for coated metal foams. It was revealed that a maximum increase of the Nusselt number by a factor of approximately 13 was obtainable in turbulent flow if the viscous flow within the washcoat was accounted for. The present study may provide a guide for structured catalyst and reactor design for strongly exothermic/endothermic catalytic processes.

      PubDate: 2016-12-19T18:22:31Z
       
  • Pore-scale simulation of effects of coal wettability on bubble-water flow
           in coal cleats using lattice Boltzmann method
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Jie Yi, Huilin Xing
      We study the effects of coal wettability on gas bubble/water two-phase flow behaviour in micro-cleats of the coal seam gas reservoir using a free energy based two-phase lattice Boltzmann model. The model is validated by comparison with analytical results and published results, and good agreement is achieved in general. Then we use this model to simulate bubble-water flow in both smooth capillary and a capillary with a narrow throat to systematically study the influences of contact angle, capillary pressure and bubble size on the flow behaviour. The simulation results indicate that both the bubble size and contact angle have significant impacts on the flow capacity of bubble and water, especially in a channel with a narrow throat. A decrease in water flow rate is observed when larger bubbles occur, and the water flow rate increases when the gas wettability becomes stronger. The bubble flow dynamics significantly influence the drainage of water and the further gas production.

      PubDate: 2016-12-19T18:22:31Z
       
  • Effect of residual lignins present in cholinium ionic liquid-pretreated
           rice straw on the enzymatic hydrolysis of cellulose
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Yan-Xia An, Min-Hua Zong, Song-Qing Hu, Ning Li
      To provide deep insights into cholinium ionic liquid (IL) pretreatment effect on the subsequent enzymatic hydrolysis, residual lignins (RLs) present in rice straw pretreated by cholinium glycinate ([Ch][Gly]), acetate ([Ch][OAc]), and glycolate ([Ch][Glc]) were isolated and characterized in this work. The effects of RLs on the enzymatic hydrolysis of cellulose and cellobiose, and their non-productive adsorption to β-glucosidase and cellulase were explored. Of the three RLs examined, RL isolated from [Ch][Gly]-pretreated straw (Gly-RL) had the highest carboxylic acid content (1.27mmol/g) and the lowest phenolic hydroxyl content (0.72mmol/g), resulting in the weakest non-productive enzyme adsorption. It might account well for the highest enzymatic digestibility of cellulose in the presence of Gly-RL. However, the strongest enzyme adsorption was found in the case of Glc-RL with the lowest carboxylic acid content (0.14mmol/g) and the highest phenolic hydroxyl content (1.19mmol/g). The enzymatic hydrolysis of cellulose was significantly affected by RLs. The negative effect of RLs on the cellulose hydrolysis mainly stemmed from their inhibition to cellulase-mediated reactions, instead of inhibition to β-glucosidase-catalyzed cellobiose hydrolysis.
      Graphical abstract image

      PubDate: 2016-12-19T18:22:31Z
       
  • Influence of pipeline modeling in stability analysis for severe slugging
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): G.R. Azevedo, J.L. Baliño, K.P. Burr
      In this paper a numerical linear stability analysis is performed to a mathematical model for the two-phase flow in a pipeline-riser system. Most of dynamic models and stability criteria are based on a simplified lumped parameter pipeline, where it is assumed that the void fraction variations can be neglected. As a pipeline with a constant void fraction is not able to describe the flow pattern transition or void fraction propagation waves, the choice of pipeline model influences the stability map. Three different models for the pipeline are considered: (a) A lumped parameter model with constant void fraction; (b) A lumped parameter model with time dependent void fraction; (c) A distributed parameter model, with void fraction dependent on time and position. The results show that the constant void fraction model overestimates the unstable region, pushing the near horizontal branch of the stability boundary beyond the stratified-intermittent transition boundary for high buffer lengths and invalidating the model assumptions. The distributed parameter model is capable of describing void fraction waves along the pipeline under the restriction of a stratified flow pattern, with an additional stabilizing effect, being less sensitive to high buffer lengths and not crossing the stratified-intermittent transition in the nearly horizontal branch. The lumped parameter model with variable void fraction behaves close to the distributed model, but predicting bigger unstable regions. The behavior of the different pipeline models is explained based on the basic assumptions that led to many semi-empirical stability criteria. It is concluded that a distributed parameter model is recommended, with a void fraction correlation that includes the transition from stratified to intermittent flow pattern taken into account in the problem statement.

      PubDate: 2016-12-13T18:17:15Z
       
  • Effect of photocatalyst film geometry on radiation absorption in a solar
           reactor, a multiscale approach
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Patricio J. Valadés-Pelayo, Camilo A. Arancibia-Bulnes, Iván Salgado-Tránsito, Heidi I. Villafán-Vidales, Manuel I. Peña-Cruz, Antonio E. Jiménez-González
      A multiscale model is presented to describe the radiation absorption field in photocatalytic reactors with supported catalyst. The characteristic matrix method is applied at the photocatalyst layer scale, and is embedded within a Monte Carlo ray tracing method, applied at the photoreactor scale. This approach allows to account for important design parameters, such as photocatalyst layer thickness, location of supporting surfaces, and incoming radiation profiles, among others. To resolve the validity of the characteristic matrix method for the description of the optical properties of the catalyst, modeled transmittance and reflectance of the supported films is compared to experimental data. This comparison is carried out for different wavelengths and film thicknesses. Afterwards, the model is applied to a solar reactor with anatase TiO 2 catalyst films supported on multiple surfaces. The reactor consists of a compound parabolic concentrator with a tubular borosilicate glass receiver. Smaller glass tubes coated with the catalyst are located inside this receiver. With the developed model, a study is conducted to analyze the reactor optical performance as a function of two important design variables: TiO 2 film thickness and radius of the absorber tubes. The results of the model indicate directions for the improvement of the current design.

      PubDate: 2016-12-13T18:17:15Z
       
  • Modeling of droplet dispersion in a turbulent Taylor–Couette flow
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Dmitry Eskin, Shawn David Taylor, Dingzheng Yang
      A process of dispersion of droplets in a developed turbulent Taylor-Couette flow is modeled. An apparatus, where the inner cylinder rotates whereas outer one is immobile, is considered. To exclude the effect of Taylor vorticities on a turbulent flow pattern, only flow regimes characterized by relatively high Reynolds numbers (>13,000) are investigated. Relatively dilute dispersions are modeled: the maximum droplet volume fraction does not exceed 10%. The time-dependent droplet size distribution in a Taylor-Couette device is described by an advection-diffusion equation containing a population balance term. Both breakup and coalescence of droplets are taken into account. An experimentally verified engineering model of a turbulent Taylor-Couette flow, based on the Prandtl mixing length theory, is used for calculating velocity, eddy diffusivity and turbulence energy dissipation rate distributions across a Taylor-Couette device gap. The known breakup and coalescence models of Coulaloglou and Tavlarides are employed for population balance modeling. However, the breakup model has been modified to account more accurately for turbulence – droplet interactions. The governing model equations are solved numerically. The computed droplet size distributions are compared with those obtained in the laboratory Taylor-Couette device in the presence of emulsion stabilizing surfactants for different rotation speeds and stirring durations. The dispersion process in a Taylor-Couette flow in both the presence and absence of surfactants is illustrated by numerical examples. The results of simulations and experiments are critically analyzed.

      PubDate: 2016-12-13T18:17:15Z
       
  • Impact of inter- and intra-molecular movements on thermoset polymerization
           reactions
    • Abstract: Publication date: 6 April 2017
      Source:Chemical Engineering Science, Volume 161
      Author(s): Harith Al-Moameri, Rima Ghoreishi, Galen Suppes
      The large increase in viscosity during thermoset reactions leads to reduced frequencies of reacting moiety collisions with respective reduced reaction rates. Molecular diffusion substantially ends after the gel point; however, reactions continue after the gel point through mechanisms involving local movement (and reacting moiety contact) of polymer sections/branches which is referred to as intra-molecular movement. The impact of inter- and intra-molecular movements was simulated for polyurethane reactions to better understand the impact of mass transfer on polymerization reactions. Inter-molecular reaction mechanisms are dominant prior to the gel point, and intra-molecular mechanisms are dominant after the gel point. Representing the Arrhenius pre-exponential factor as a sum of a viscosity-dependent term and a viscosity-independent term was identified as the most efficient method to model this phenomenon. Good agreement of simulation results for reaction temperature, foam height, and viscosity profile with the experimental data were obtained.
      Graphical abstract image

      PubDate: 2016-12-13T18:17:15Z
       
 
 
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